Hi,

I am looking to repeat the power calculation found in this protocol (sample size text attached): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4950103/

The trial is a 2 group, 2 measure study (baseline & follow-up), comparing change in a biomarker (HbA1c). The estimated clinically relevant difference is 0.5%, with a cross-sectional SD of 1.1 and correlation of 0.4. The power is set to 90%.

I try to repeat this using the following:

Code:
power repeated 0 0 \ 0 0.5, factor(bwithin) corr(0.4) varerror(1.21) power(0.9)
But I think I am misunderstanding something as my results differ. Does anyone have advice on how to perform this calculation?

Thank you very much,
Megan


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